world the increase would be much larger. I have made the same calculation for Ceylon, starting with the 1961 population, supposing that 1961 death rates were maintained, and that the birth rates immediately dropped to the level which would secure a stationary population in the long run. The total would increase from just over 10 million in 1961 to well over 15 million by the year 2011. Of course this is less than the threefold or more that it would grow if the 1961 birth rates continued, but it is nonetheless a great deal. For Latin America, with a history of higher birth rates, the momentum of past growth would be even greater. If Colombia had dropped its births to the stationary level in 1965 when its population was 18 million, it would have risen to a stationary number of 29.8 million, a rise of over 65 percent. Ecuador of 1965 would have gone up by 66.7 percent; Peru of 1963 by 56.9 percent. Insofar as infant deaths have declined in recent years, the percent rise to the stationary population from a jumping-off point in the 1970's would be higher. If the drop in births extends over a period rather than occurring at one moment, then the ultimate stationary population will be correspondingly higher. (See Table 2.) TABLE 2 Current and Ultimate Stationary Populations on Assumption That Birth Rates Drop Immediately to Stationary Level Percent Increase Current Ultimate to Ultimate Canada 1968 20,264,000 28,562,000 40.9 Chile 1 965 8,584,000 12,916,000 50.5 Colombia 1965 17,993,000 29,786,000 65.5 Ecuador 1965 5,109,000 8,518,000 66.7 Ireland 1968 2,910,000 3,684,000 26.6 Italy 1966 53,128,000 62,189,000 17.1 Trinidad and Tobago 1967 1,015,000 1,633,000 60.9 United States 1966 195,857,000 259,490,000 32.5 Source: Author's calculations. The impact of a one-time fall in the birth rates would be different at different ages. First a decline in the number of young children would appear. The United States projection at stationary rates from 1966 would show a drop in children under 5 of 25 percent, from 20 million to 14.5 million; the number would then go up again to over 19 million by 1986, as women fromOne would take the view that there is only so much land, water, air, minerals, and other facilities, and set the birth target so that each individual who died would be replaced. I do not know that anyone has seriously argued that at the present time this is the appropriate policy, but with high enough density it could come to be so. Precisely in order to avoid such a requirement at some time in the future, it seems necessary to put the brakes on now (3).